Current theories of the cause of
Alzheimer's disease (AD) do not address the question as to why AD
patients initially and gradually lose their short-term memory,
followed later by progressive and accelerated loss of other
memory, language, motor skills, perception and very short-term
memory. We propose that this pattern of memory loss may be
a result of a REM sleep deficit or malfunction. This
hypothesis is also supported by :

(1)Results which show that AD
patients have less REM sleep than controls.

(2)There is an established
close correspondence between learning/memory and REM sleep.REM sleep deprivation is known to result in (mild) impairment in
learning recent information.

(3)AD patients have a
degenerated cholinergic system of the brain.The
cholinergic system is known to activate/stimulate the REM sleep
process.

(4)The lesions in AD victims
are primarily located in those regions of the brain that are
considered to be active during REM sleep.

(5)There is a natural
mechanism by which the REM sleep in humans is reduced from 8
hours each day at birth to less than one hour each day in old
age.An acceleration of this process can lead to possible
REM deficit at old age.Furthermore, since old people have
so little REM sleep they are more vulnerable to a REM sleep
deficit.

The REM sleep deficit
mechanism may also work in conjunction with other theories of the
etiology of AD, in which case, the REM sleep deficit may explain
the progression and/or the acceleration of memory loss in AD.If our ideas are correct, it offers hope that the memory loss in
AD may be alleviated or reduced by prolonged periods of increased
REM sleep.REM sleep deficit may also be useful for early
diagnosis of AD disease.Our hypothesis can be tested by
more detailed studies of the amount of REM sleep in patients with
AD, particularly in the early stages of the disease.

Here is a link
to some drugs used to treat Alzheimers's disease. Note that the first 3
are cholinesterase inhibitors work by slowing down the process that
breaks down a key neurotransmitter. Donepezil, galantamine and
rivastigmine are cholinesterase inhibitors.